Product Overview

The Allen-Bradley 1756-IH16I belongs to the trusted ControlLogix series. This module provides 16 individually isolated digital inputs. It operates with a 125V DC sink/source voltage category. The 1756-IH16I handles rugged industrial environments reliably. It supports an operating voltage range of 90-146V DC. Each input point isolates itself from others for safety. This design reduces electrical noise and ground loop errors. You can use this module in high-voltage DC monitoring applications.

Technical Specifications

Input Characteristics

– Number of Inputs: 16 individually isolated points
– Voltage Category: 125V DC sink/source
– Operating Voltage Range: 90-146V DC
– Nominal Input Voltage: 125V DC
– On-State Current: 1 mA minimum at 90V DC to 3 mA maximum at 146V DC
– Off-State Voltage Maximum: 20V DC
– Off-State Current Maximum: 0.8 mA
– Inrush Current Maximum: 250 mA

Timing and Response

– Delay Off to On: 2 ms hardware plus selected filter (0,1,2 ms)
– Delay On to Off: 6 ms hardware plus selected filter (0,1,2,9,18 ms)
– User-Selectable Filter Times: Yes, per module configuration

Power and Dissipation

– Backplane Current at 5.1V: 125 mA
– Backplane Current at 24V: 3 mA
– Total Backplane Power: 0.71 W
– Maximum Power Dissipation: 5 W at 60°C
– Thermal Dissipation: 17.05 BTU/hour

Isolation and Environment

– Isolation (Input to Input): 250V continuous
– Temperature Range: 0°C to 60°C (32°F to 140°F)
– Module Type: Digital Isolated Input Module
– Series: ControlLogix

Installation Guide

Follow these steps to install the 1756-IH16I correctly.
1. Remove chassis power before inserting any module.
2. Set the module’s keying position using the provided pins.
3. Slide the 1756-IH16I into an empty ControlLogix slot.
4. Press the top and bottom locking tabs firmly.
5. Attach a compatible removable terminal block (RTB).
6. Use either 1756-TBCH or 1756-TBS6H RTB.
7. Wire each input according to the sink/source diagram.
8. Verify on-state current reaches at least 1 mA per point.
9. Apply 90-146V DC only to avoid damage.
10. Restore power and check module status indicators.

Package Contents

– One Allen-Bradley 1756-IH16I ControlLogix module
– One installation instructions sheet (printed)
– One set of keying pins (pre-installed)
– No RTB included (order 1756-TBCH or 1756-TBS6H separately)

Frequently Asked Questions (FAQ)

1. What chassis is compatible with the 1756-IH16I?

The 1756-IH16I fits any standard ControlLogix 1756 chassis. It works with 4, 7, 10, or 17-slot racks.

2. Can I mix this module with 24V DC inputs?

No, the 1756-IH16I requires 90-146V DC only. Use 1756-IB series modules for 24V DC applications.

3. How do I reduce false triggering from noise?

Select a higher input filter time (up to 18 ms). This rejects transient noise on isolated input channels.

4. Does the module support hot swapping?

Yes, the 1756-IH16I supports insertion under power (RIUP). Follow proper ESD precautions during removal.

5. What indicates a healthy module?

The green OK LED stays solid. A red LED means internal fault or missing backplane communication.

Compliance and Reliability

The Allen-Bradley 1756-IH16I meets global industrial standards. It offers high resistance to electrical noise. Each of the 16 points isolates from the others. This prevents a single fault from shutting down all inputs. The wide 90-146V DC range supports unstable power sources. Use this module for high-voltage monitoring, relay status, and limit switches. Its low 5W dissipation allows dense chassis layouts without overheating.